Hi,
On 4/3/20 12:57 PM, André Przywara wrote:
> On 26/03/2020 15:24, Alexandru Elisei wrote:
>
> Hi,
>
>> From: Alexandru Elisei <alexandru.elisei@xxxxxxxxx>
>>
>> Implement callbacks for activating and deactivating emulation for a BAR
>> region. This is in preparation for allowing a guest operating system to
>> enable and disable access to I/O or memory space, or to reassign the
>> BARs.
>>
>> The emulated vesa device framebuffer isn't designed to allow stopping and
>> restarting at arbitrary points in the guest execution. Furthermore, on x86,
>> the kernel will not change the BAR addresses, which on bare metal are
>> programmed by the firmware, so take the easy way out and refuse to
>> activate/deactivate emulation for the BAR regions. We also take this
>> opportunity to make the vesa emulation code more consistent by moving all
>> static variable definitions in one place, at the top of the file.
>>
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
>> ---
>> hw/vesa.c | 70 ++++++++++++++++++++------------
>> include/kvm/pci.h | 18 ++++++++-
>> pci.c | 44 ++++++++++++++++++++
>> vfio/pci.c | 100 ++++++++++++++++++++++++++++++++++++++--------
>> virtio/pci.c | 90 ++++++++++++++++++++++++++++++-----------
>> 5 files changed, 254 insertions(+), 68 deletions(-)
>>
>> diff --git a/hw/vesa.c b/hw/vesa.c
>> index 8071ad153f27..31c2d16ae4de 100644
>> --- a/hw/vesa.c
>> +++ b/hw/vesa.c
>> @@ -18,6 +18,31 @@
>> #include <inttypes.h>
>> #include <unistd.h>
>>
>> +static struct pci_device_header vesa_pci_device = {
>> + .vendor_id = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET),
>> + .device_id = cpu_to_le16(PCI_DEVICE_ID_VESA),
>> + .header_type = PCI_HEADER_TYPE_NORMAL,
>> + .revision_id = 0,
>> + .class[2] = 0x03,
>> + .subsys_vendor_id = cpu_to_le16(PCI_SUBSYSTEM_VENDOR_ID_REDHAT_QUMRANET),
>> + .subsys_id = cpu_to_le16(PCI_SUBSYSTEM_ID_VESA),
>> + .bar[1] = cpu_to_le32(VESA_MEM_ADDR | PCI_BASE_ADDRESS_SPACE_MEMORY),
>> + .bar_size[1] = VESA_MEM_SIZE,
>> +};
>> +
>> +static struct device_header vesa_device = {
>> + .bus_type = DEVICE_BUS_PCI,
>> + .data = &vesa_pci_device,
>> +};
>> +
>> +static struct framebuffer vesafb = {
>> + .width = VESA_WIDTH,
>> + .height = VESA_HEIGHT,
>> + .depth = VESA_BPP,
>> + .mem_addr = VESA_MEM_ADDR,
>> + .mem_size = VESA_MEM_SIZE,
>> +};
>> +
>> static bool vesa_pci_io_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
>> {
>> return true;
>> @@ -33,24 +58,19 @@ static struct ioport_operations vesa_io_ops = {
>> .io_out = vesa_pci_io_out,
>> };
>>
>> -static struct pci_device_header vesa_pci_device = {
>> - .vendor_id = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET),
>> - .device_id = cpu_to_le16(PCI_DEVICE_ID_VESA),
>> - .header_type = PCI_HEADER_TYPE_NORMAL,
>> - .revision_id = 0,
>> - .class[2] = 0x03,
>> - .subsys_vendor_id = cpu_to_le16(PCI_SUBSYSTEM_VENDOR_ID_REDHAT_QUMRANET),
>> - .subsys_id = cpu_to_le16(PCI_SUBSYSTEM_ID_VESA),
>> - .bar[1] = cpu_to_le32(VESA_MEM_ADDR | PCI_BASE_ADDRESS_SPACE_MEMORY),
>> - .bar_size[1] = VESA_MEM_SIZE,
>> -};
>> -
>> -static struct device_header vesa_device = {
>> - .bus_type = DEVICE_BUS_PCI,
>> - .data = &vesa_pci_device,
>> -};
>> +static int vesa__bar_activate(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + /* We don't support remapping of the framebuffer. */
>> + return 0;
>> +}
>>
>> -static struct framebuffer vesafb;
>> +static int vesa__bar_deactivate(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + /* We don't support remapping of the framebuffer. */
>> + return -EINVAL;
>> +}
>>
>> struct framebuffer *vesa__init(struct kvm *kvm)
>> {
>> @@ -73,6 +93,11 @@ struct framebuffer *vesa__init(struct kvm *kvm)
>>
>> vesa_pci_device.bar[0] = cpu_to_le32(vesa_base_addr | PCI_BASE_ADDRESS_SPACE_IO);
>> vesa_pci_device.bar_size[0] = PCI_IO_SIZE;
>> + r = pci__register_bar_regions(kvm, &vesa_pci_device, vesa__bar_activate,
>> + vesa__bar_deactivate, NULL);
>> + if (r < 0)
>> + goto unregister_ioport;
>> +
>> r = device__register(&vesa_device);
>> if (r < 0)
>> goto unregister_ioport;
>> @@ -87,15 +112,8 @@ struct framebuffer *vesa__init(struct kvm *kvm)
>> if (r < 0)
>> goto unmap_dev;
>>
>> - vesafb = (struct framebuffer) {
>> - .width = VESA_WIDTH,
>> - .height = VESA_HEIGHT,
>> - .depth = VESA_BPP,
>> - .mem = mem,
>> - .mem_addr = VESA_MEM_ADDR,
>> - .mem_size = VESA_MEM_SIZE,
>> - .kvm = kvm,
>> - };
>> + vesafb.mem = mem;
>> + vesafb.kvm = kvm;
>> return fb__register(&vesafb);
>>
>> unmap_dev:
> Those transformations look correct to me.
>
>> diff --git a/include/kvm/pci.h b/include/kvm/pci.h
>> index adb4b5c082d5..1d7d4c0cea5a 100644
>> --- a/include/kvm/pci.h
>> +++ b/include/kvm/pci.h
>> @@ -89,12 +89,19 @@ struct pci_cap_hdr {
>> u8 next;
>> };
>>
>> +struct pci_device_header;
>> +
>> +typedef int (*bar_activate_fn_t)(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data);
>> +typedef int (*bar_deactivate_fn_t)(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data);
>> +
>> #define PCI_BAR_OFFSET(b) (offsetof(struct pci_device_header, bar[b]))
>> #define PCI_DEV_CFG_SIZE 256
>> #define PCI_DEV_CFG_MASK (PCI_DEV_CFG_SIZE - 1)
>>
>> -struct pci_device_header;
>> -
>> struct pci_config_operations {
>> void (*write)(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> u8 offset, void *data, int sz);
>> @@ -136,6 +143,9 @@ struct pci_device_header {
>>
>> /* Private to lkvm */
>> u32 bar_size[6];
>> + bar_activate_fn_t bar_activate_fn;
>> + bar_deactivate_fn_t bar_deactivate_fn;
>> + void *data;
>> struct pci_config_operations cfg_ops;
>> /*
>> * PCI INTx# are level-triggered, but virtual device often feature
>> @@ -162,6 +172,10 @@ void pci__config_rd(struct kvm *kvm, union pci_config_address addr, void *data,
>>
>> void *pci_find_cap(struct pci_device_header *hdr, u8 cap_type);
>>
>> +int pci__register_bar_regions(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> + bar_activate_fn_t bar_activate_fn,
>> + bar_deactivate_fn_t bar_deactivate_fn, void *data);
>> +
>> static inline bool __pci__memory_space_enabled(u16 command)
>> {
>> return command & PCI_COMMAND_MEMORY;
>> diff --git a/pci.c b/pci.c
>> index 611e2c0bf1da..4ace190898f2 100644
>> --- a/pci.c
>> +++ b/pci.c
>> @@ -66,6 +66,11 @@ void pci__assign_irq(struct device_header *dev_hdr)
>> pci_hdr->irq_type = IRQ_TYPE_EDGE_RISING;
>> }
>>
>> +static bool pci_bar_is_implemented(struct pci_device_header *pci_hdr, int bar_num)
>> +{
>> + return pci__bar_size(pci_hdr, bar_num);
>> +}
>> +
>> static void *pci_config_address_ptr(u16 port)
>> {
>> unsigned long offset;
>> @@ -273,6 +278,45 @@ struct pci_device_header *pci__find_dev(u8 dev_num)
>> return hdr->data;
>> }
>>
>> +int pci__register_bar_regions(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> + bar_activate_fn_t bar_activate_fn,
>> + bar_deactivate_fn_t bar_deactivate_fn, void *data)
>> +{
>> + int i, r;
>> + bool has_bar_regions = false;
>> +
>> + assert(bar_activate_fn && bar_deactivate_fn);
>> +
>> + pci_hdr->bar_activate_fn = bar_activate_fn;
>> + pci_hdr->bar_deactivate_fn = bar_deactivate_fn;
>> + pci_hdr->data = data;
>> +
>> + for (i = 0; i < 6; i++) {
>> + if (!pci_bar_is_implemented(pci_hdr, i))
>> + continue;
>> +
>> + has_bar_regions = true;
>> +
>> + if (pci__bar_is_io(pci_hdr, i) &&
>> + pci__io_space_enabled(pci_hdr)) {
>> + r = bar_activate_fn(kvm, pci_hdr, i, data);
>> + if (r < 0)
>> + return r;
>> + }
> Indentation seems to be off here, I think the last 4 lines need to have
> one tab removed.
>
>> +
>> + if (pci__bar_is_memory(pci_hdr, i) &&
>> + pci__memory_space_enabled(pci_hdr)) {
>> + r = bar_activate_fn(kvm, pci_hdr, i, data);
>> + if (r < 0)
>> + return r;
>> + }
> Same indentation issue here.
Nicely spotted, I'll fix it.
>
>> + }
>> +
>> + assert(has_bar_regions);
> Is assert() here really a good idea? I see that it makes sense for our
> emulated devices, but is that a valid check for VFIO?
> From briefly looking I can't find a requirement for having at least one
> valid BAR in general, and even if - I think we should rather return an
> error than aborting the guest here - or ignore it altogether.
The assert here is to discover coding errors with devices, not with the PCI
emulation. Calling pci__register_bar_regions and providing callbacks for when BAR
access is toggled, but *without* any valid BARs looks like a coding error in the
device emulation code to me.
As for VFIO, I'm struggling to find a valid reason for someone to build a device
that uses PCI, but doesn't have any BARs. Isn't that the entire point of PCI? I'm
perfectly happy to remove the assert if you can provide an rationale for building
such a device.
>
>> +
>> + return 0;
>> +}
>> +
>> int pci__init(struct kvm *kvm)
>> {
>> int r;
>> diff --git a/vfio/pci.c b/vfio/pci.c
>> index 8b2a0c8dbac3..18e22a8c5320 100644
>> --- a/vfio/pci.c
>> +++ b/vfio/pci.c
>> @@ -8,6 +8,8 @@
>> #include <sys/resource.h>
>> #include <sys/time.h>
>>
>> +#include <assert.h>
>> +
>> /* Wrapper around UAPI vfio_irq_set */
>> union vfio_irq_eventfd {
>> struct vfio_irq_set irq;
>> @@ -446,6 +448,81 @@ out_unlock:
>> mutex_unlock(&pdev->msi.mutex);
>> }
>>
>> +static int vfio_pci_bar_activate(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + struct vfio_device *vdev = data;
>> + struct vfio_pci_device *pdev = &vdev->pci;
>> + struct vfio_pci_msix_pba *pba = &pdev->msix_pba;
>> + struct vfio_pci_msix_table *table = &pdev->msix_table;
>> + struct vfio_region *region;
>> + bool has_msix;
>> + int ret;
>> +
>> + assert((u32)bar_num < vdev->info.num_regions);
>> +
>> + region = &vdev->regions[bar_num];
>> + has_msix = pdev->irq_modes & VFIO_PCI_IRQ_MODE_MSIX;
>> +
>> + if (has_msix && (u32)bar_num == table->bar) {
>> + ret = kvm__register_mmio(kvm, table->guest_phys_addr,
>> + table->size, false,
>> + vfio_pci_msix_table_access, pdev);
>> + if (ret < 0 || table->bar != pba->bar)
> I think this second expression deserves some comment.
> If I understand correctly, this would register the PBA trap handler
> separetely below if both the MSIX table and the PBA share a BAR?
The MSIX table and the PBA structure can share the same BAR for the base address
(that's why the MSIX capability has an offset field for both of them), but we
register different regions for mmio emulation because we don't want to have a
generic handler and always check if the mmio access was to the MSIX table of the
PBA structure. I can add a comment stating that, sure.
>
>> + goto out;
> Is there any particular reason you are using goto here? I find it more
> confusing if the "out:" label has just a return statement, without any
> cleanup or lock dropping. Just a "return ret;" here would be much
> cleaner I think. Same for other occassions in this function and
> elsewhere in this patch.
>
> Or do you plan on adding some code here later? I don't see it in this
> series though.
The reason I'm doing this is because I prefer one exit point from the function,
instead of return statements at arbitrary points in the function body. As a point
of reference, the pattern is recommended in the MISRA C standard for safety, in
section 17.4 "No more than one return statement", and is also used in the Linux
kernel. I think it comes down to personal preference, so unless Will of Julien
have a strong preference against it, I would rather keep it.
>
>> + }
>> +
>> + if (has_msix && (u32)bar_num == pba->bar) {
>> + ret = kvm__register_mmio(kvm, pba->guest_phys_addr,
>> + pba->size, false,
>> + vfio_pci_msix_pba_access, pdev);
>> + goto out;
>> + }
>> +
>> + ret = vfio_map_region(kvm, vdev, region);
>> +out:
>> + return ret;
>> +}
>> +
>> +static int vfio_pci_bar_deactivate(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + struct vfio_device *vdev = data;
>> + struct vfio_pci_device *pdev = &vdev->pci;
>> + struct vfio_pci_msix_pba *pba = &pdev->msix_pba;
>> + struct vfio_pci_msix_table *table = &pdev->msix_table;
>> + struct vfio_region *region;
>> + bool has_msix, success;
>> + int ret;
>> +
>> + assert((u32)bar_num < vdev->info.num_regions);
>> +
>> + region = &vdev->regions[bar_num];
>> + has_msix = pdev->irq_modes & VFIO_PCI_IRQ_MODE_MSIX;
>> +
>> + if (has_msix && (u32)bar_num == table->bar) {
>> + success = kvm__deregister_mmio(kvm, table->guest_phys_addr);
>> + /* kvm__deregister_mmio fails when the region is not found. */
>> + ret = (success ? 0 : -ENOENT);
>> + if (ret < 0 || table->bar!= pba->bar)
>> + goto out;
>> + }
>> +
>> + if (has_msix && (u32)bar_num == pba->bar) {
>> + success = kvm__deregister_mmio(kvm, pba->guest_phys_addr);
>> + ret = (success ? 0 : -ENOENT);
>> + goto out;
>> + }
>> +
>> + vfio_unmap_region(kvm, region);
>> + ret = 0;
>> +
>> +out:
>> + return ret;
>> +}
>> +
>> static void vfio_pci_cfg_read(struct kvm *kvm, struct pci_device_header *pci_hdr,
>> u8 offset, void *data, int sz)
>> {
>> @@ -805,12 +882,6 @@ static int vfio_pci_create_msix_table(struct kvm *kvm, struct vfio_device *vdev)
>> ret = -ENOMEM;
>> goto out_free;
>> }
>> - pba->guest_phys_addr = table->guest_phys_addr + table->size;
>> -
>> - ret = kvm__register_mmio(kvm, table->guest_phys_addr, table->size,
>> - false, vfio_pci_msix_table_access, pdev);
>> - if (ret < 0)
>> - goto out_free;
>>
>> /*
>> * We could map the physical PBA directly into the guest, but it's
>> @@ -820,10 +891,7 @@ static int vfio_pci_create_msix_table(struct kvm *kvm, struct vfio_device *vdev)
>> * between MSI-X table and PBA. For the sake of isolation, create a
>> * virtual PBA.
>> */
>> - ret = kvm__register_mmio(kvm, pba->guest_phys_addr, pba->size, false,
>> - vfio_pci_msix_pba_access, pdev);
>> - if (ret < 0)
>> - goto out_free;
>> + pba->guest_phys_addr = table->guest_phys_addr + table->size;
>>
>> pdev->msix.entries = entries;
>> pdev->msix.nr_entries = nr_entries;
>> @@ -894,11 +962,6 @@ static int vfio_pci_configure_bar(struct kvm *kvm, struct vfio_device *vdev,
>> region->guest_phys_addr = pci_get_mmio_block(map_size);
>> }
>>
>> - /* Map the BARs into the guest or setup a trap region. */
>> - ret = vfio_map_region(kvm, vdev, region);
>> - if (ret)
>> - return ret;
>> -
>> return 0;
>> }
>>
>> @@ -945,7 +1008,12 @@ static int vfio_pci_configure_dev_regions(struct kvm *kvm,
>> }
>>
>> /* We've configured the BARs, fake up a Configuration Space */
>> - return vfio_pci_fixup_cfg_space(vdev);
>> + ret = vfio_pci_fixup_cfg_space(vdev);
>> + if (ret)
>> + return ret;
>> +
>> + return pci__register_bar_regions(kvm, &pdev->hdr, vfio_pci_bar_activate,
>> + vfio_pci_bar_deactivate, vdev);
>> }
>>
>> /*
>> diff --git a/virtio/pci.c b/virtio/pci.c
>> index d111dc499f5e..598da699c241 100644
>> --- a/virtio/pci.c
>> +++ b/virtio/pci.c
>> @@ -11,6 +11,7 @@
>> #include <sys/ioctl.h>
>> #include <linux/virtio_pci.h>
>> #include <linux/byteorder.h>
>> +#include <assert.h>
>> #include <string.h>
>>
>> static u16 virtio_pci__port_addr(struct virtio_pci *vpci)
>> @@ -462,6 +463,64 @@ static void virtio_pci__io_mmio_callback(struct kvm_cpu *vcpu,
>> virtio_pci__data_out(vcpu, vdev, addr - mmio_addr, data, len);
>> }
>>
>> +static int virtio_pci__bar_activate(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + struct virtio_device *vdev = data;
>> + u32 bar_addr, bar_size;
>> + int r = -EINVAL;
>> +
>> + assert(bar_num <= 2);
>> +
>> + bar_addr = pci__bar_address(pci_hdr, bar_num);
>> + bar_size = pci__bar_size(pci_hdr, bar_num);
>> +
>> + switch (bar_num) {
>> + case 0:
>> + r = ioport__register(kvm, bar_addr, &virtio_pci__io_ops,
>> + bar_size, vdev);
>> + if (r > 0)
>> + r = 0;
>> + break;
>> + case 1:
>> + r = kvm__register_mmio(kvm, bar_addr, bar_size, false,
>> + virtio_pci__io_mmio_callback, vdev);
>> + break;
>> + case 2:
>> + r = kvm__register_mmio(kvm, bar_addr, bar_size, false,
>> + virtio_pci__msix_mmio_callback, vdev);
> I think adding a break; here looks nicer.
Sure, it will make the function look more consistent.
Thanks,
Alex
>
> Cheers,
> Andre
>
>
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static int virtio_pci__bar_deactivate(struct kvm *kvm,
>> + struct pci_device_header *pci_hdr,
>> + int bar_num, void *data)
>> +{
>> + u32 bar_addr;
>> + bool success;
>> + int r = -EINVAL;
>> +
>> + assert(bar_num <= 2);
>> +
>> + bar_addr = pci__bar_address(pci_hdr, bar_num);
>> +
>> + switch (bar_num) {
>> + case 0:
>> + r = ioport__unregister(kvm, bar_addr);
>> + break;
>> + case 1:
>> + case 2:
>> + success = kvm__deregister_mmio(kvm, bar_addr);
>> + /* kvm__deregister_mmio fails when the region is not found. */
>> + r = (success ? 0 : -ENOENT);
>> + }
>> +
>> + return r;
>> +}
>> +
>> int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>> int device_id, int subsys_id, int class)
>> {
>> @@ -476,23 +535,8 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>> BUILD_BUG_ON(!is_power_of_two(PCI_IO_SIZE));
>>
>> port_addr = pci_get_io_port_block(PCI_IO_SIZE);
>> - r = ioport__register(kvm, port_addr, &virtio_pci__io_ops, PCI_IO_SIZE,
>> - vdev);
>> - if (r < 0)
>> - return r;
>> - port_addr = (u16)r;
>> -
>> mmio_addr = pci_get_mmio_block(PCI_IO_SIZE);
>> - r = kvm__register_mmio(kvm, mmio_addr, PCI_IO_SIZE, false,
>> - virtio_pci__io_mmio_callback, vdev);
>> - if (r < 0)
>> - goto free_ioport;
>> -
>> msix_io_block = pci_get_mmio_block(PCI_IO_SIZE * 2);
>> - r = kvm__register_mmio(kvm, msix_io_block, PCI_IO_SIZE * 2, false,
>> - virtio_pci__msix_mmio_callback, vdev);
>> - if (r < 0)
>> - goto free_mmio;
>>
>> vpci->pci_hdr = (struct pci_device_header) {
>> .vendor_id = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET),
>> @@ -518,6 +562,12 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>> .bar_size[2] = cpu_to_le32(PCI_IO_SIZE*2),
>> };
>>
>> + r = pci__register_bar_regions(kvm, &vpci->pci_hdr,
>> + virtio_pci__bar_activate,
>> + virtio_pci__bar_deactivate, vdev);
>> + if (r < 0)
>> + return r;
>> +
>> vpci->dev_hdr = (struct device_header) {
>> .bus_type = DEVICE_BUS_PCI,
>> .data = &vpci->pci_hdr,
>> @@ -548,20 +598,12 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
>>
>> r = device__register(&vpci->dev_hdr);
>> if (r < 0)
>> - goto free_msix_mmio;
>> + return r;
>>
>> /* save the IRQ that device__register() has allocated */
>> vpci->legacy_irq_line = vpci->pci_hdr.irq_line;
>>
>> return 0;
>> -
>> -free_msix_mmio:
>> - kvm__deregister_mmio(kvm, msix_io_block);
>> -free_mmio:
>> - kvm__deregister_mmio(kvm, mmio_addr);
>> -free_ioport:
>> - ioport__unregister(kvm, port_addr);
>> - return r;
>> }
>>
>> int virtio_pci__reset(struct kvm *kvm, struct virtio_device *vdev)
>>
